The embodiment relates to a light emitting device, a method of manufacturing the same, a light emitting device package, and a lighting system.
A light emitting device (LED) includes a p-n junction diode having a characteristic of converting electric energy into light energy. The p-n junction diode can be formed by combining group III-V elements of the periodic table. The LED may represent various colors by adjusting the compositional ratio of compound semiconductors.
When forward voltage is applied to the LED, electrons of an n layer are bonded with holes of a p layer, so that energy corresponding to an energy gap between a conduction band and a valance band may be generated. This energy is mainly realized as heat or light, and the LED emits the energy as the light.
A nitride semiconductor represents superior thermal stability and wide band gap energy so that the nitride semiconductor has been spotlighted in the field of optical devices and high-power electronic devices. In particular, blue, green, and UV light emitting devices employing the nitride semiconductor have already been developed and extensively used.
In a GaN-based light emitting diode (LED) according to the related art, in order to improve light emitting efficiency, light efficiency is further improved through a design of an active layer, and then a work of improving extraction efficiency is performed so that optimization is achieved.
According to the relate art, a patterned sapphire substrate (PSS) using a pattern on a substrate is used at a lower portion of a light emitting device chip, and roughening is used at an upper portion of the light emitting device chip so that light extraction efficiency may be improved. However, according to the demand of a high output light emitting device, the improvement in the light extraction efficiency is required.